As a cure for our addiction to oil, ethanol turns out to have some nasty side effects.

Pollution from gasoline engines accounts for 10,000 deaths in the US each year, along with thousands of cases of respiratory disease and even cancer. The widely touted ethanol-based fuel E85 (15 per cent gasoline, 85 per cent ethanol) could make matters worse.

Mark Jacobson of Stanford University in California modelled emissions for cars expected to be on the road in 2020. The model assumed that carbon emissions would be 60 per cent less than 2002 levels, so overall deaths would be halved. However, an E85-fuelled fleet would cause 185 more pollution-related deaths per year than a petrol one across the US, most of them in Los Angeles.

The findings, to be published in Environmental Science & Technology, run
counter to the idea that ethanol is a cleaner-burning fuel. While ethanol-burning cars will emit fewer carcinogens such as benzene and butadiene, they will spew out 20 times as much acetaldehyde as those using conventional fuel. Acetaldehyde can react with sunlight to form ozone, one of the main constituents of smog, and so increase the risks to people's health.

Without the predicted 60 per cent emissions cut it will be worse. "If we went
on today's emissions, there could be two-and-a-half times more damage,"
Jacobson says. "There are so many people barking pretty loud about biofuels. They've been pushing these things before the science is done. Now the question is: will people listen?"